Method and apparatus for cutting elastomeric materials

ABSTRACT

A method and apparatus for cutting segments from a long sheet ( 1 ) of multilayered elastomeric material. An initial opening is formed in the sheet without severing reinforcing cords ( 20 ) within the elastomeric sheet by a penetrator/separator ( 40 ). Two ultrasonic knives are inserted on either side of the penetrator/separator ( 40 ) and positioned to cut the sheet at a small skive angle a with respect to the plane of the sheet being cut. Then the knives are moved to opposite edges of the sheet of elastomeric material.

BACKGROUND OF THE INVENTION

[0001] 1. Technical Field

[0002] This invention relates to methods and apparatus for cuttingelastomeric materials at low skive angles, in particular cutting layeredcomposites of elastomeric materials including layers containingreinforcing materials.

[0003] 2. Background of the Invention

[0004] Various methods and apparatus have been used for the cutting ofsheets of elastomeric material. Such elastomeric material might consistof single sheets of homogeneous material, or multiple layered sheets ofmaterials having properties that are different from one another. In thecase of multiple layered sheets of elastomeric material that, forvarious reasons, need to be cut, one or more of the layers might containreinforcing cords or fibers made of metal or fabric. Such reinforcingcords or fibers might be part of a woven reinforcing fabric, or theymight be simply aligned in such a way as to be parallel to one another.Furthermore, the elastomeric materials that are to be cut may or may notbe cured or vulcanized at the time of cutting.

[0005] Prior art cutting methods and apparatus include cutting wheels,ultrasonic cutters, scissor type cutters, guillotine knives, wirecutters and vibrating scroll cutters whose active cutting principle is asaw blade or a tensioned wire.

[0006] While such prior art cutting methods are effective to varyingdegrees, each as disadvantages. For example, the guillotine knife issomewhat effective in cutting composite elastomeric materials, but ithas the disadvantage of having a tendency to deform the cut surfaces ofthe elastomeric material as the knife penetrates the material. Suchdeformation of the cut edge increases the difficulty of subsequentsplicing the ends of the elastomeric material. Moreover, the guillotineknife produces a continually degraded cut surface as the blade becomesdull and/or as small pieces of elastomer began to build up on the blade.Yet another disadvantage was the inability of the blade to cut at anangle less than 30 degrees relative to the plane of the material beingcut. The guillotine blade also tends to generate heat during the cuttingprocess such that, as numerous cuts are made, the temperature of theknife becomes sufficiently elevated in some cases to induce precuring ofunvulcanized elastomer in the region of the cut, which then inhibitssubsequent proper splicing the cut edges.

[0007] Another prior art cutting system and method, disclosed in U.S.Pat. No. 5,638,732, employs a cutting wire. This system could not,however, be used to cut preassembled elastomeric composite sheetscontaining reinforcing cords because the reinforcing cords themselves,though aligned more or less parallel to the direction of the cut, getsevered. This deficiency is actually inherent to nearly every prior artcutting technology (including ultrasonic knives) that cut compositeelastomeric preassemblies at relatively low skive angles. That is tosay, nearly all prior art cutting methods tended to cut theparallel-aligned cords that are used to reinforce one or more layers ofreinforced ply. (The cut is, ideally, intended to be made between theparallel-aligned reinforcing cords.) The only prior art exception beingthe scroll cutter, which could cut at low skive angles without alsorisking cutting the reinforcing cords.

[0008] The scroll cutter cannot, however, initiate its cut within thecentral region of a sheet of preassembled composite elastomeric sheets,because of its geometry, which includes a wire held at each end by afixture. The scroll cutter must start its cut from the side of thepreassembly, such that the cutting has difficulty entering the plywithout splitting the reinforcing cords. Even at a 90 degree skiveangle, the reliability of not splitting cords is in question. At lowskive angles it becomes exponentially difficult to enter the ply withoutsplitting a ply cord. Sometimes the reinforced ply end will be buriedunder the other layers, such as, in the case of tire manufacturing, thesidewall layer or other layers such as the extreme edge of thepreassembly within the context of envelope construction. This addsanother dimension of difficulty for the wire scroll cutter to cutreliably preassembly with reinforced layers, such as specifically theply of tires.

[0009] Ultrasonic cutting systems as disclosed in U.S. Pat. No.5,265,508, can cut stock material at low skive angles. However, theyrequire that the material be secured to an anvil during cutting.

[0010] Another system, disclosed in U.S. Pat. No. 4,922,774, employs anultrasonic cutting device which vibrates a knife that moves across anelastomeric strip. However, this system is limited to cutting angles ofbetween 10 and 90 degrees, and it does not provide for cutting betweenparallel disposed, reinforcement cords within the strip, which is tosay, the cords can get cut.

[0011] A significant problem with the prior art cutting systems andmethods is the inability to cut at angles less than 30 degrees relativeto the plane of the elastomeric layers being cut without deformation orprecuring the material. This can be a problem in, for example, automatedtire building operations wherein the cutting has to be done preciselyand quickly and where the cutter can also provide improvements to thecut surface which is subsequently to be spliced.

[0012] An ideal cutting method and apparatus should be able to make cutsat low angles (relative to the plane of the elastomeric sheet beingcut),,and it should be able to do so without cutting theparallel-aligned reinforcing cords between which the cutter is ideallyto move. It should also be able to make these low angle cuts rapidly andreliably.

OBJECTS OF THE INVENTION

[0013] It is an object of the present invention to provide method andapparatus for cutting single or multilayered flat sheets of elastomericmaterials, one or more layers of which are reinforced with cords whichare aligned parallel to one another and oriented in the direction of thecut, the method and apparatus being as defined in one or more of theappended claims and, as such, having the capability of being constructedto accomplish one or more of the following subsidiary objects.

[0014] One object of the present invention to provide a method andapparatus for cutting segments of cord-reinforced elastomeric materialfrom long, multilayered flat sheets of cord-reinforced elastomericmaterial, such method and apparatus overcoming the disadvantages andlimitations of the prior art methods and devices.

[0015] Another object of the present invention to provide a method andapparatus for cutting segments of material from long multilayered flatsheets of cord-reinforced elastomeric material without cutting thereinforcing cords that are more or less aligned with the direction ofthe cut.

[0016] It is another object of the present invention to provide a methodand apparatus for cutting segments of material from long multilayeredflat sheets of cord-reinforced elastomeric materials by initiating thecut at a location that is between the lateral edges of the sheet ofelastomeric material.

[0017] Yet another object of the present invention to provide a methodand apparatus for initiating the cutting segments of material frommultilayered flat sheets of cord-reinforced elastomeric materialswithout cutting the reinforcing cords.

[0018] Another object of the present invention to provide a method andapparatus for cutting segments of material from long multilayered flatsheets of cord-reinforced elastomeric materials by the controllablepenetration of the cutting knifes such as to perform the cutting in asuch a way that intentionally dulled edges of the cutting knives are inclose proximity to the reinforcing cords, thereby protecting thereinforcing cords from being cut.

[0019] Another object of the present invention is to provide a methodand apparatus for cutting segments of material from long multilayeredflat sheets of cord-reinforced elastomeric materials at skive or cuttingangles that can be varied between angles of about 5 degrees and about 40degrees with respect to the plane of the sheet.

[0020] Still another object of the present invention to provide methodand apparatus for cutting segments of material from long multilayeredflat sheets of cord-reinforced elastomeric materials at skive angles orcutting angles that can be controllably varied between about 5 degreesand about 40 degrees with respect to the plane of the sheet at thebeginning of the cutting operation; and

[0021] Finally another object of the present invention to provide methodand apparatus for cutting segments from long multilayered flat sheets ofcord-reinforced elastomeric materials at skive or cutting angles whichcan be varied between angles of about 5 degrees and about 40 degreeswith respect to the plane of the sheet during the cutting operation.

SUMMARY OF THE INVENTION

[0022] The invention herein described is a method for cutting segmentsof elastomeric material from a long sheet of multilayered elastomericmaterial, at least one layer of which contains parallel alignedreinforcing cords. The cutting method employs the use of apenetrator/separator and two ultrasonic knives of a double-edged,stiletto type. The penetrator/separator makes an initial opening in thesheet of elastomeric material, penetrating it while separating, withoutsevering, the reinforcing cords. The tip of the penetrator/separator canbe heated to facilitate penetration, and the tip is blunt or dulled tominimize the potential for severing the parallel-aligned, reinforcingcords. The sides of the penetrator/separator are tapered so that theopening created in the elastomeric sheet can be controllably widenedaccording to the depth to which the penetrator/separator is insertedinto and through the opening it creates. The initial penetration is madeat some location inwards of the two sides of the sheet being cut. Thepenetrator/separator is initially substantially perpendicular to thesheet being penetrated. After the opening is made in the elastomericsheet, the two ultrasonic knives are inserted into the opening, one oneither side of the penetrator/separator. The two knives might beinserted into the opening before they and the penetrator/separator areangularly reoriented to an angle of less than 90 degrees, i.e. between 5degrees and 40 degrees, with respect to the plane of the elastomericsheet being cut, or the two knives might be inserted into the openingafter the penetrator/separator has been angularly reoriented to an angleof less than 90 degrees with respect to the plane of the elastomericsheet being cut. The ultrasonic knives, after insertion and angularadjustment, make the cut by moving apart from one another and from thepenetrator/separator. The skive angle or cutting angle of the knives canbe adjusted during the cutting process, each knife independently of theother or in concert with the other. The skive angle of each knife isadjustable between about 5 degrees and about 40 degrees within the planeperpendicular to the direction of the cut. The depth to which eachultrasonic knife is inserted into the elastomeric sheet is controllable.The tip of each ultrasonic knife blade is dulled to minimize thepotential for cutting of the parallel-aligned reinforcing cords mostadjacent to the line along with the cut is being made.

[0023] Other benefits and advantages of the invention will becomeapparent to those skilled in the art to which it pertains upon a readingand understanding of the following detailed specification.

BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The structure, operation, and advantages of the invention willbecome further apparent upon consideration of the following descriptiontaken in conjunction with the accompanying drawings, wherein:

[0025]FIG. 1 is a schematic view of a conveyor conveyed multilayeredsheet of elastomeric material, showing the location of the cut to bemade;

[0026]FIG. 2 is a detailed view of one type of layered structure of theelastomeric sheet shown in FIG. 1;

[0027]FIG. 3A is a side view of an ultrasonic cutting knive;

[0028]FIG. 3B is an edge view of an ultrasonic cutting knive;

[0029]FIG. 4 shows an elastomeric sheet with two cutting knives locatedon either side of the penetrator separator;

[0030]FIG. 5A is an edge view of an elastomeric sheet, demonstrating theskive angle of the cut;

[0031]FIG. 5B is an edge view of an elastomeric sheet having beenpenetrated by a penetrator/separator;

[0032]FIG. 5C is an edge view of an elastomeric sheet in which thepenetrator/separator has been angularly positioned to less than 90degrees with respect to the plane of the sheet;

[0033]FIG. 5D is an edge view of an elastomeric sheet in which thepenetrator/separator has been angularly positioned to less than 90degrees with respect to the plane of the sheet and a knife has beeninserted beside the penetrator/separator;

[0034]FIG. 6A is an oblique schematic view of a piece of multilayeredelastomeric material being wrapped around a tire building drum; and

[0035]FIG. 6B is an orthogonal, end-on view of the building drum shownin FIG. 6A.

DEFINITIONS

[0036] “Bead” or “Bead Core” generally means that part of the tirecomprising an annular tensile member of circumerentially wound wires orcables associated with holding the tire on a wheel rim.

[0037] “Belt Structure” or “Reinforcement Belts” or “Belt Package” meansat least two annular layers or plies of parallel cords, woven orunwoven, underlying the tread, unanchored to the bead, and having bothleft and right cord angles in the range from 18° to 30° relative to theequatorial plane of the tire.

[0038] “Breakers” or “Tire Breakers” means the same as belt or beltstructure or reinforcement belts.

[0039] “Carcass” means the tire structure apart from the belt structure,tread, undertread over the plies, but including the beads.

[0040] “Casing” means the carcass, belt structure, beads, sidewalls andall other components of the tire excepting the tread and undertread.

[0041] “Circumferential” most often means circular lines or directionsextending along the perimeter of the surface of the annular treadperpendicular to the axial direction; it can also refer to the directionof the sets of adjacent circular curves whose radii define the axialcurvature of the tread, as viewed in cross section.

[0042] “Cord” means one of the reinforcement strands, including fibers,which are used to reinforce the plies.

[0043] “Inner Liner” means the layer or layers of elastomer or othermaterial that form the inside surface of a tubeless tire and thatcontain the inflating fluid within the tire.

[0044] “Insert” means the crescent- or wedge-shaped reinforcementtypically used to reinforce the sidewalls of runflat-type tires; it alsorefers to the elastomeric non-crescent-shaped insert that underlies thetread.

[0045] “Ply” means a cord-reinforced layer of elastomer-coated, radiallydeployed or otherwise parallel cords.

[0046] “Radial Ply Structure” means the one or more carcass plies orwhich at least one ply has reinforcing cords oriented at an angle ofbetween 65° and 90° with respect to the equatorial plane of the tire.

[0047] “Radial Ply Tire” means a belted or circumferentially-restrictedpneumatic tire in which at least one ply has cords which extend frombead to bead are laid at cord angles between 65° and 90° with respect tothe equatorial plane of the tire.

[0048] “Sidewall” means that portion of a tire between the tread and thebead.

[0049] “Skive” or “skive angle” refers to the cutting angle of a knifewith respect to the material being cut; the skive angle is measured withrespect to the plane of the flat material being cut.

[0050] “Tread Cap” refers to the tread and the underlying material intowhich the tread pattern is molded.

[0051] “Wedge Insert” means the same as “Insert.”

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

[0052] With reference to FIG. 1, a sheet 1 of elastomeric material isillustrated in oblique view. The sheet 1 has a width W and an indefinitelength designated by the L direction. The sheet 1 is transported upon aconveyor means (not shown) in the direction D. The sheet 1 comprises oneor more elastomeric layers. The dotted line 3 shows the location of alateral cut that is to be made across the width of the sheet 1 ofelastomeric material. The conveyor system (not shown) which supports thesheet 1 does not convey the sheet during the cutting process, but ratheronly supports the sheet during this operation.

[0053]FIG. 2 is a cross-sectional view of a sheet 1 of a multilayeredelastomeric material, comprising three layers 5. That is, FIG. 2 shows anot-to-scale schematic view of the structural details of a typicalelastomeric sheet 1 of the sort shown generally in FIG. 1. The layers 5includes, in FIG. 2, an innerliner elastomeric layer 10, acord-reinforced elastomeric ply layer 12, and two spaced-apart sidewalllayers 14 and 16. Reinforcing cords 20 are located within the ply layer12. The reinforcing cords 20 are disposed essentially parallel to oneanother, and are oriented at right angles to the respective sides 4 aand 4 b of sheet 1 of the layered elastomeric shown in FIGS. 1 and 2. Inother words, the reinforcing cords 20 of the ply layer 12 are orientedlaterally across the width W of the plane of the sheet 1 of the layeredelastomeric material, and are perpendicular to the direction L andparallel to the direction of line 3 along which the cut will be made.

[0054] One of the challenges faced in cutting such a sheet ofelastomeric material is to make the cut in such a way so as not to cutany of the ply reinforcing cords 20. Worth noting in this regard is thatthe reinforcing cords 20 might not be accessible to direct view from theedge-on view as shown in FIG. 2, which is to say, the otherwise exposedends of the reinforcing cords might actually be covered with othermaterials or elastomeric layers at the edges of the sheet 1 shown inFIG. 2. The fact that the reinforcing cords 20 might not be visible whenviewed from the edge of the sheet 1 works against initiating the cuttingprocess at one of the edges 4 a or 4 b for two reasons: (1) such anedge-initiated cut might sever an underlying reinforcing cord; and (2)the process of initiating the cut at the edge, even if the reinforcingcords are not cut, has the potential to disrupt the lay of thereinforcing cords in such a way as to adversely affect the quality ofthe final product that is subsequently manufactured from the cut sheetof elastomeric material. With special regard to the latter possibility(of deforming the edge of the material being cut), the cut can beinitiated, such that the least effect on the quality of the finalproduct, at a specific location inward of the edges 4 a, 4 b of theelastomeric sheet. Which is to say, flaws resulting from the initiationof the cut can more easily be accommodated within the final product ifthe cut is initiated somewhere along the dotted line 3 that is inward ofthe edges 4 a, 4 b.

[0055] Accordingly, the cutting method achieved by the present inventioninvolves an initial penetration of the elastomeric sheet by means of apenetrator/separator 40, which separates the two mutually adjacentreinforcing cords 20 that are closest to the point of penetration. Thepenetrator/separator 40 is discussed in more detail below.

[0056]FIGS. 3A and 3B show two views of a double-bladed, stiletto-typeultrasonic knife assembly 30, comprising a blade 32 having two opposingcutting edges 34 a, 34 b, a supporting handle 36 and a shank 38 thatattaches to a computer controlled mechanical knife holder 39 that alsoconveys ultrasonic energy to the knife blade 32. The computer-controlledmechanical knife holder 39, the details of which do not form a part ofthe present invention, also holds and controls the penetrator/separator40, which is shown in FIG. 4; the computer-controlled knife andpenetrator holder controls the translational and angular motions of theknives and the penetrator/separator, as well as the cutting depth towhich the knives reach into the elastomeric material. FIG. 3A shows theblade 32 from a side-on view; FIG. 3B shows the blade 32 edge-on. Theedges 34 a, 34 b of the portion of the blade 32 near the tip or “horn”31 are dulled for reasons that will be described below.

[0057] Sequence of the Cutting Operation

[0058] Referring now to FIG. 4, an elastomeric sheet 1 is shown beingcut. The cutting process takes place while the sheet 1 is held in placeand stationary by the conveyor system (not shown) upon which the sheethas been transported into position prior to cutting. The cutting processis initiated by inserting the penetrator/separator 40 through theelastomeric sheet 1, thereby piercing it. The penetrator/separator 40has a dulled, heated tip which allows penetration of the sheet 1 in sucha way that the embedded reinforcing cords that are most adjacent to thepoint of penetration are separated without being severed by thepenetrator/separator 40. FIG. 5B shows the penetrator/separator 40 froma direction that corresponds to an edge-on view of the sheet 1 beingcut. Adjacent cords 17,18 are separated without being cut by thepenetrator/separator 40. Evident also in FIGS. 5A, 5B, 5C, 5D (5A-5D)are the tapered sides 41 and heated tip 42 of the penetrator/separator40.

[0059] Referring to FIG. 4, two ultrasonic knives 30 are insertedthrough the opening 331 one blade each on either side of thepenetrator/separator 40. The penetrator/separator 40, having taperedsides, can be inserted into the opening 33 to a depth that creates anopening of sufficient width for the knives to be inserted. The nowinserted knives 30 then make their respective cuts at a skive angle α.The skive angle α shown in FIGS. 4 and 5A is the actual cutting angle,as measured between each knife's axis and the plane of the elastomericsheet 1. More specifically, the skive angle α is the cutting angle asmeasured inside of the plane that is perpendicular to the direction ofthe cut being made, and it is the angle between the cutting edges ofeach knife and the plane of the sheet of material being cut. Once theinserted knives are angularly oriented to the desired skive angle α, thecutting can thence proceed as the two mechanically controlled ultrasoniccutting blades are moved away from one another along the line 3 whichdefines the direction of the desired cut.

[0060] Referring to FIGS. 5A through 5B, once the initial penetrationhas taken place and the two reinforcing cords 17,18 that are closest tothe point of penetration, and which lie on either side of the point ofpenetration, have been pushed aside or separated (FIGS. 5B and 5C), thecutting blades 32 of the ultrasonic knives 30 can then be inserted oneither side of the point of the initial penetration. However, after theinitial penetration has taken place and before the cutting begins,consideration must be made for achieving the proper skive angle orcutting angle α. The skive angle or cutting angle α can vary betweenabout 5 and about 40 degrees, even though the initial penetration ofpenetrator/separator 40 is made at an angle that is close toperpendicular to the sheet 1 of elastomeric material. More preferablythe skive angle α is between about 5 degrees and about 20 degrees.

[0061] The actual cutting operation can follow one of two sequencesafter the initial penetration has been made by the penetrator/separator40.

[0062] Referring to FIG. 5B, the penetrator/separator 40 is initiallyoriented more or less at right angles to the plane of the sheet 1.Accordingly, there are two methods by which to orient the cutting blades32 prior to initiation of cutting at the desired skive angle α are:

[0063] Method 1—The penetrator/separator 40, after having penetrated thesheet 1 at more or less right angles, can be oriented to the desiredangle α, as shown in FIG. 4C, after which the blades 32 of theultrasonic knives 30 can be inserted; or

[0064] Method 2—The blades 32 of the ultrasonic knives 30 can beinserted at an orientation that is more or less perpendicular to theplane of the sheet 1, and then the combination of the two knives and thepenetrator/separator 40 can be simultaneously oriented to the skiveangle α, as shown in FIGS. 4 and 5D.

[0065] By whichever method of knife insertion and orientation to thedesired skive angle α, the two ultrasonic knives 30, after insertioninto the opening 33, are moved apart from one another along the cuttingline 3 shown in FIGS. 1, 2, and 4. The cut is thus made at the desiredskive angle, with the cut having been initiated at such a location aswill cause minimal disruption of the structure of the elastomeric sheet1, thereby having the least adverse effect on the quality of the finalproduct that is to be manufactured from the cut sheet.

[0066] The penetrator/separator 40 is maintained in its location andskive angle orientation throughout the cutting process in order to holdthe cut edges and the underlying reinforcing cords 20 apart from oneanother during the cutting process.

[0067] The Dulled Tips of the Cutting Blades

[0068] More or fewer than three layers might constitute a particularlayered elastomeric sheet 1 that is to be cut in the lateral directionshown by the dotted line 3 in FIGS. 1 and 2. FIGS. 1 and 2 show aspecific example of a three-layered type of multilayered elastomericmaterial that is to be cut. In particular, the types of elastomericsheet 1 that are to be cut will have an indefinite length L and has somedefinite width W. In addition, the elastomeric sheet is fed along aconveyor system (not shown) in the direction D, and the sheet is stoppedperiodically to allow the widthwise cut along the line 3.

[0069]FIGS. 3A and 3B, which show, respectively, the side and edge-onviews of an ultrasonic cutting-knife assembly 30 illustrate the stilettonature of the cutting blade 32. The stiletto nature of the blades allowsthe cutting process to take place in such a way that the cut materialcan “flow” around the blade, thereby inducing the least amount ofdistortion in the cut edge of the elastomeric material. Each ultrasonicknife assembly 30 attaches by means of the shank 38 into the chuck (notshown) of a conventional computer-controlled machine (not shown) thatdelivers ultrasonic energy to the knife and controls the cutting angleof the knife and the translational motion of the knife as each blade 32progresses edgewise along the direction of the cut. However, the tip orhorn 31 of the knife blade 32 is dull compared to other parts of thecutting blade. This relative dullness relates to the depth to which eachcutting blade 32 is inserted into and through the sheet 1 of theelastomeric material; more specifically, each knife is inserted to sucha depth that the dulled part of the tip or horn 31 of the blade will beclosest to the depth location within the elastomeric material whereinlie the reinforcing cords 20. In other words, the dulled part of the tip31 of the blades will be in the region of the elastomeric material thatcontains the reinforcing cords, and the dulled blade will be less likelyto sever the reinforcing cords 20 during the cutting process. Thus apoint worth noting about this invention: the depth to which each cuttingblade can be inserted into and through the elastomeric material is, likethe skive angle and the cutting speed, controllable by means of thecomputer-controlled mechanical device that holds and controls the bladesand the penetrator/separator and which conveys ultrasonic energy to thecutting knives.

[0070] The depth to which the knives 30 are inserted into theelastomeric material 1 are controllable independently of one anotherduring the cutting process.

[0071] Controlling the Skive Angle

[0072] The cutting challenges addressed by the present invention includethe above-mentioned presence of the reinforcing cords 20 and the varyingthickness of the elastomeric layers, such as the sidewall layers 14 and16 shown in FIG. 2. One goal of the present invention is to cut thelayered elastomeric sheet 1 without cutting the parallel-alignedreinforcing cords 20 which are oriented more or less in the direction ofthe cut that is to be made. Additionally, the cut is to be made at asmall skive angle α, for reasons described below.

[0073] The skive angle α is shown in FIG. 5A, which shows across-sectional edge-on view of a sheet 1 of layered elastomericmaterial; i.e., the skive angle α is the cutting angle between the planeof sheet 1 and the line A-A. Incidently, the views shown in FIGS. 5A-5Dcorrespond to the direction of the reinforcing cords 20, which is alsothe direction of the cut; in other words, the direction of the cut isperpendicular to the plane of the FIGS. 5A-5D. Accordingly the anglewhich each of the two knife blades 30 has with the plane of theelastomeric material, during the cutting process, is the skive angle αof that blade. The skive angle α is between about 5 degrees and about 40degrees and the skive angle of each blade is independently variable ofthe other blade during the cutting process. That is, the controllermachine (not shown) which holds the cutting two knives is able tocontrol the skive angles of each knife during the cutting processindependently of one another.

[0074] Small skive angles α create a large surface in the cut face ofthe elastomeric material. Such a large surface area is important in thefinal use to which the cut elastomeric material is to be put;specifically, each cut piece of elastomeric material is to be wrappedaround a tire-building drum in such a way that the respective severededges can be brought together in a way that allows them to be splicedalong a large contact area as shown schematically in FIGS. 6A and 6B.

[0075] While FIGS. 5A through 5D show three layers of elastomericmaterial in the sheet 1 (as also shown in FIG. 2), more than three orfewer than three layers might also be at issue in some types of sheetsof elastomeric material that are to be cut. FIG. 5B shows thepenetrator/separator 40, the tip of which is blunt and heated, after ithas been pushed through the elastomeric material without cutting thereinforcing cords 20. As shown in FIG. 4, the penetrator/separator 40penetrates the multi-layered elastomeric sheet 1 at some location inwardof the edges 4 a and 4 b. The blunt end of the penetrator/separator 40is designed to push aside, or separate, the adjacent reinforcing cords20 between which the initial penetration takes place. The tapered sides41 of the penetrator/separator allow the penetrator/separator to becontrollably inserted so as to controllably widen the gap 33 into whichthe knives 30 are to be inserted.

[0076]FIG. 4 shows the ultrasonic knife assemblies 30 inserted into theopening 33 created by the penetrator/separator 40 in the elastomericsheet 1. Penetrator/separator 40 is shown in the location where theinitial penetration has taken place within the sheet 1. The knifeassemblies 30 are thence inserted on either side of thepenetrator/separator 40, as shown, and thence moved laterally apart fromone another in the directions indicated by the arrows A and B. Arrow Cindicates the direction of movement of the elastomeric sheet, prior toand after the cutting process, along the conveyor system (which is notshown and which is not in motion during the cutting process). The skiveangle α is also shown.

[0077] While the initial angle of piercing by the penetrator/separator40 is about 90 degrees to the plane of the sheet 1, the goal of theinvention is to make the cut at a small skive angle α. The reason forthe small skive angle α relates to the subsequent manufacturing step,mentioned above, in which the cut ends of the multilayered elastomericsheets are to be spliced together. The nature of the splicing isillustrated in FIGS. 6A and 6B. FIG. 6A shows a cut sheet 62 wrappedaround a tire-building drum 60. The respective cut edges 64 a, 64 b,i.e., the edges which have been cut at a low skive angle α, can bejoined or spliced along a larger surface area of contact than would bepossible had the cut been made at a steep skive angle α. FIG. 6B showsthe tire-building drum 60 end-on, with the cut sheet of elastomericmaterial 62 wrapped around it and the cut ends spliced together atlocation 64.

[0078] Adjustment of the skive angle a during the cutting process is anadditional feature of this invention. That is to say, the inventionanticipates that cuts might be made at steeper angles a at certainlocations along the cutting line 3 shown in FIGS. 1, 2 and 4. Forexample, referring to FIG. 2, the skive angle a might be larger in thethicker regions of the sheet 1 where the sidewall layers 14,16 arelocated, than in the locations where the sheet is thinner. Larger skiveangles α in such thicker locations will still provide large areas ofcontact when the respective ends of the cut sheet is wrapped around thetire building drum of the sort shown in FIGS. 6 and 6B.

[0079] While the invention has been described in combination withembodiments thereof, it is evident that many alternatives,modifications, and variations will be apparent to those skilled in theart in light of the foregoing teachings. Accordingly, the invention isintended to embrace all such alternatives, modifications and variationsas fall within the spirit and scope of the appended claims.

What is claimed:
 1. A method for cutting segments from a long sheet (1)of multilayered elastomeric material containing reinforcing cords (20)that are more or less parallel to one another and oriented more or lessin the direction of a cut line (3), the method including the steps of:penetrating the sheet (1) and making an opening(33) with apenetrator/separator(40); inserting two ultrasonic knives (30) intoopening (33), one on either side of the penetrator/separator; moving theknives (30) apart from the penetrator/separator (40) and apart from oneanother in opposite directions along the cut line (3) of the cut beingmade; and cutting the segments at a desired skive angle α.
 2. The methodof claim 1 including the step of penetrating into the sheet with aheated tip of the penetrator/separator (40).
 3. The method of claim 1including the step of penetrating into the sheet with a dulled tip ofthe penetrator/separator (40).
 4. The method of claim 1 including thestep of penetrating the sheet with the penetrator/separator (40) havingtapered sides.
 5. The method of claim 4 including the step of cuttingthe sheet with the two opposing cutting edges of the ultrasonic knives(30).
 6. The method of claim 1 including the step of controlling theskive angle a of the ultrasonic knives (30) before initiation of thecutting step.
 7. The method of claim 6 including the step of controllingthe skive angles a of the ultrasonic knives (30) during the cuttingstep.
 8. The method of claim 7 including the step of controlling therespective skive angle α of the each ultrasonic knife (30) independentlyof the other during the cutting step.
 9. The method of claim 1 includingthe step of controlling the depth of penetration of thepenetrator/separator (40).
 10. The method of claim 1 including the stepof controlling the respective depths of penetration of the ultrasonicknives (30).
 11. The method of claim 1 including the step of controllingthe angle of the penetrator/separator (40) subsequent to the step ofpenetrating the sheet of elastomeric material to between about 90degrees and about 5 degrees.
 12. The method of claim 2 including thestep of inserting the ultrasonic knives (30) into the opening (33)created by the penetrator/separator (40) prior to the angularreorientation of the penetrator/separator to an angle of less than 90degrees.
 13. The method of claim 1 including the step of inserting theultrasonic knives (30) into the opening (33) created by thepenetrator/separator (40) subsequent to the angular reorientation of thepenetrator/separator to an angle of less than 90 degrees.
 14. Anapparatus for cutting segments from a long sheet (1) of multilayeredelastomeric material containing reinforcing cords (20) that are more orless parallel to one another and oriented more or less in the directionof a cut line (3), the apparatus characterized by: apenetrator/separator (40) for penetrating the sheet to form an opening(33); two ultrasonic knives (30) for inserting into opening (33) one oneither side of the penetrator/separator; and means for moving the knives(30) apart from the penetrator/separator (40) and apart from one anotherin opposite directions along the cut line (3) of the cut being made. 15.The apparatus of claim 14 further characterized by thepenetrator/separator (40) having a heated tip (31).
 16. The appatarus ofclaim 14 further characterized the penetrator/separator (40) having adull tip (31).
 17. The apparatus of claim 14 further characterized bythe penetrator/separator (40) having tapered sides.